THE ADVANCE OF SCIENCE 123 



Hereafter, the well-ascertained laws of experimental 

 psychology will undoubtedly furnish the necessary scien- 

 tific basis of the art of education, and psychology will 

 hold the same relation to that art as physiology does to 

 the art of medicine and hygiene. 



There can be little doubt, moreover, of the valuable 

 interaction of the study of physical psychology and the 

 theories of the origin of structural character by natural 

 selection. The relation of the human mind to the mind 

 of animals, and the gradual development of both, form 

 a subject full of rich stores of new material, yielding 

 conclusions of the highest importance, which has not 

 yet been satisfactorily approached. 



I am glad to be able to give wider publicity here to 

 some conclusions which I communicated to the Jubilee 

 volume of the ' Societe de Biologic ' of Paris in 1899. 

 I there discussed the significance of the great increase in 

 the size of the cerebral hemispheres in recent, as com- 

 pared with Eocene Mammals (see fig. 5), and in Man as 

 compared with Apes, and came to the conclusion that ' the 

 power of building up appropriate cerebral mechanism in 

 response to individual experience,' or what may be called 

 ' educability,' is the quality which characterizes the larger 

 cerebrum, and is that which has led to its selection, 

 survival, and further increase in volume. The bearing of 

 this conception upon questions of fundamental importance 

 in what has been called genetic psychology is sketched as 

 follows : 



' The character which we describe as " educability " 

 can be transmitted; it is a congenital character. But the 

 results of education can not be transmitted. In each 

 generation they have to be acquired afresh. With 

 increased " educability " they are more readily acquired 

 and a larger variety of them. On the other hand, the 



